Unit galenical formulation for local hormonotherapy of vaginal dryness

ABSTRACT

A galenical formulation is intended for local, essentially non systemic, treatment of vaginal dryness, in particular in the menopausal woman. It comprises a free natural estrogen, in particular a micronized or vectorized estrogen, selected from 17β-estradiol and its salts in solution or in suspension in a lipophilic agent, with an estrogen content which corresponds to an equivalent unit dose of at most 15 μg, preferably less than 10 μg, of 17β-estradiol, a hydrophilic gel-forming bioadhesive agent, a gelling agent for the lipophilic agent and a hydrodispersible agent. The soft capsule form comprises a hard or soft outer envelope containing gelatin and glycerine and a non aqueous liquid or semi-liquid inner phase containing the lipophilic agent with the estrogen in solution or in suspension, the bioadhesive agent and the hydrophilic gelling agent for the lipophilic agent. The slow release vaginal suppository comprises a non aqueous hard or semi-soft solid homogeneous phase containing the lipophilic agent with the estrogen in solution or in suspension, the hydrophilic bioadhesive gel-forming agent, the gelling agent for the lipophilic agent and the hydrodispersible agent.

The invention concerns a medicament for local, essentially non systemic,treatment of vaginal dryness.

The problems of vaginal dryness, in particular in the menopausal woman,are known: dyspareunia, urogenital atrophy which can cause problems withthe urinary function, and risks of infection due to an insufficientlydeveloped flora.

One aim of the invention is to provide a medicament which is suitablefor essentially non systemic treatment, which is thus distinguished fromsubstitutive hormonotherapy treatments where the hormone can beadministered per os, transcutaneously or intravaginally.

In contrast, European patent EP-A-0 103 995 and U.S. Pat. No. 5,019,395describe galenical formulations for general hormonotherapy where thecompositions contain high doses of active principle, respectively 4% to15% by weight and 0.1% to 8% by weight of the medicament.

In particular, the medicament of the invention is distinguished fromvaginally administered substitutive hormonotherapy medicaments in theform, for example, of vaginal creams, tablets, or suppositories whichcontain high doses of estrogens. Such cases simply take advantage of thefact that systemic passage is better when administered vaginally thanwhen administered orally, in particular because of the absence ofestrogen metabolization when administered vaginally.

In contrast, the invention seeks to provide a local treatment withminimal or zero systemic passage by direct use of a natural estrogen, inparticular 17β-estradiol, to alleviate local problems by avoidingsecondary systemic effects which may occur in certain patients, inparticular the occurrence of endometrial hyperplasia.

Local treatments of this type have already been proposed, for example inthe form of a vaginal ring in the form of a torus comprising an estrogenwhich diffuses through the porous membrane of the ring, thus enablingcontinuous release over a long period.

In common with all intravaginal devices, however, such rings have thedisadvantage of necessitating the presence of a non degradable foreignbody in the organism and of requiring insertion and removalmanipulations.

A galenical formulation comprising 17β-estradiol in the form of vaginaltablets which are administered daily has also been proposed for suchlocal treatment. Such tablets contain a matrix comprising an excipientsuch as a cellulosic polymer which absorbs traces of residual vaginalmoisture to impregnate the matrix containing the active principle andgradually release the latter.

However, because of their particular galenical form, the dosage of suchtablets must be relatively high to obtain the desired results, typicallya dosage of 25 micrograms (μg) of 17β-estradiol per tablet (one tabletcorresponds to one unit dose) to provide the desired cytological,histological and clinical improvement in the vaginal mucous membrane.Because of this relatively high dose, endometrial proliferation wasnoted in certain patients during clinical studies, indicating systemicpassage of 17β-estradiol: see in particular C. Fielding et al.,"Preoperative Treatment with Estradiol in Women Scheduled for VaginalOperation for Genital Prolapse. A Randomised, Double-Blind Trial",Maturitas, 1992, 15, 241-249.

One aim of the present invention is to propose a medicament of the abovetype with a particular galenical formulation which enables the dosage of17β-estradiol to be reduced so as to avoid systemic passage despite theextreme sensitivity of the vaginal mucous membrane to estrogens, whileensuring satisfactory trophic effectiveness.

According to the invention, this medicament is characterized by a unitgalenical formulation comprising a natural estrogen selected from17β-estradiol and its salts in solution or in suspension in a lipophilicagent, with an estrogen content which corresponds to an equivalent unitdose of at most 15 μg, preferably less than 10 μg, of 17β-estradiol, ahydrophilic gel-forming bioadhesive agent, a gelling agent for thelipophilic agent and a hydrodispersible agent.

In contact with vaginal secretions, the hydrophilic bioadhesive agentgels and the presence of the hydrodispersible agent causes the galenicalformulation to emulsify, enabling direct passive diffusion of the activeprinciple between the emulsified excipient and the vaginal mucousmembrane with which it is contact. The bioadhesive nature (or, moreprecisely, mucoadhesive nature) of the hydrophilic gelling agent allowsthe emulsion to adhere to the mucous membrane with a slight flow, thusensuring long term retention.

This long term retention can in particular enable applications to beless frequent and may thus be only once a day, or less frequent still(particularly in the maintenance phase).

The estrogen, which is advantageously micronized, can be present in thegalenical formulation either in its free form or in a vectorized form,in particular by encapsulation in nanoparticle type vectors such assupramolecular biovectors.

In a first embodiment, the medicament is in capsule form comprising ahard or soft solid outer envelope containing gelatin and a non aqueousliquid or semi-liquid inner phase containing the lipophilic agent withthe estrogen in solution or in suspension, the hydrophilic gel-formingbioadhesive agent, the gelling agent for the lipophilic agent and thehydrodispersible agent.

The capsule may be a hard capsule or, advantageously, a soft capsule,i.e., with an outer envelope containing glycerine.

Advantageously in the latter case:

the lipophilic agent is selected from liquid triglycerides;

the hydrophilic gel-forming bioadhesive agent is selected fromcarboxyvinylic acids, hydroxypropylcellulose, carboxymethylcellulose,gelatin, xanthane gum, guar gum, aluminum silicate and mixtures thereof;

the gelling agent for the lipophilic agent is hydrophobic colloidalsilica;

the hydrodispersible agent is selected from polyoxyethylene glycols,polyoxyethylene glycol 7-glyceryl-cocoate and mixtures thereof;

the composition of the inner phase is: free or vectorized micronized17β-estradiol: 2.5 μg to 15 μg; hydroxypropylcellulose: 120 mg;hydrophobic colloidal silica: 50 milligrams (mg) to 80 mg;polyoxyethylene glycol 7-glyceryl-cocoate: 400 mg; liquid triglycerides:q.s. 1600 mg.

In a further embodiment, the medicament is in the form of a slow releasevaginal suppository comprising a non aqueous hard or semi-soft solidhomogeneous phase containing the hydrophilic gel-forming bioadhesiveagent, the gelling agent for the lipophilic agent and thehydrodispersible agent.

In this case, advantageously:

the lipophilic agent is selected from solid triglycerides with a meltingpoint of about 35° C., carnauba wax, cocoa butter or mixtures thereof;

the hydrophilic gel-forming bioadhesive agent is selected fromcarboxyvinylic acids, hydroxypropylcellulose, carboxymethylcellulose,gelatin, xanthane gum, guar gum, aluminum silicate and mixtures thereof;

the gelling agent for the lipophilic agent is hydrophobic colloidalsilica;

the hydrodispersible agent is selected from polyoxyethylene glycols andmixtures thereof;

the composition is: free or vectorized micronized 17β-estradiol: 2.5 μgto 15 μg; hydroxypropylcellulose: 80 mg; hydrophobic colloidal silica: 5mg to 60 mg; polyoxyethylene glycol: 50 mg to 200 mg; carboxyvinylicacid: 8 mg; solid triglycerides: q.s. 1600 mg.

In both cases, these formulations have a number of advantages:

they are tolerated well, are stable and are galenically acceptable;

their bioadhesion can prevent flow to a maximum extent;

they ensure compatibility of vehicles with the active principle;

they encourage emulsification of the vehicle containing the activeprinciple with vaginal secretions, providing some hydrophilic character.

The different aspects of the present invention are described below inmore detail, using various examples of formulations.

Choice of Active Principle

An estrogen selected from 17β-estradiol, its salts and its derivativeswas selected for the medicament of the invention.

This group includes the family of compounds the chemical structure ofwhich has the following general formula: ##STR1##

When R═H, the compound is 17β-estradiol, which is the naturalphysiological hormone produced by the ovaries of fertile women and thelack of which is responsible for functional problems experienced in themenopausal patient.

17β-estradiol is a physiological estrogenic agonist. Its trophic effectin the vulvo-vaginal mucous membrane is recognized and has been widelydescribed, as has the reversibility of histological functional andclinical problems by administration of 17β-estradiol. Estradiol and itsderivatives (salts) reduce the vaginal pH and increase the transvaginalpotential difference, the quantity of vaginal secretions and the localblood flow.

In the female, receptors with high estradiol affinity have beendiscovered in the vaginal epithelium. These have an affinity forradio-labelled estrogen which is close to that calculated for receptorsin the myometrium but they appear to be fewer in number. These receptorsare characterized by a decreasing affinity for the following compounds:

17β-estradiol>estriol>estrone.

However, while 17β-estradiol has proved to be a pure agonist, estriol,its natural metabolite, is characterized by partially agonist propertiesand even antagonist properties. An antagonistic effect against naturalestrogen may occur.

Treatment with 17β-estradiol thus has the advantage of adding effects inthe presence of endogenous estrogen, while treatment with estriol hasthe disadvantage of having an antagonistic effect on endogenousestradiol. Further, because of its intrinsically lower activity thanthat of 17β-estradiol, estriol has proved to be less active (someauthors explain this phenomenon by a higher rate of dissociation of itsnuclear receptors). Since the activity presented by a partial agonist ismore dependent on the number of receptors than that of a completeagonist, the difference in activity between these two estrogeniccompounds is more marked since the number of vaginal tissue receptorsappears to be lower than in the myometrium.

In conclusion, in view of the high affinity of 17β-estradiol for vaginalestrogenic receptors and particularly its activity profile as a completeagonist, this natural estrogen constitutes a better choice than estriolfor obtaining a local trophic effect.

The same comments apply to estrone, which is a precursor of estriol, andto derivatives of estradiol synthesis such as the dietheroxide ofestradiol (promestriene DCI).

Choice of Dosage

The dosage must be selected so as to relieve local problems and preventtransvaginal absorption to a maximum extent.

These aims are achieved by selecting a dose of 10 μg of 17β-estradiol,corresponding to a unit dose (a single daily administration, or lessfrequently still).

When 17β-estradiol is present in this dose in a micronized free form,only slight systemic passage is observed, in the form of a simpleplasmic peak about one hour after administration; the maximum plasmicconcentration of the peak never exceeds 30 picograms per milliliter(pg/ml) but clearly it is highly transitory.

If even this very small passage is to be avoided, a first solutionconsists of reducing the amount of active principle, typically to dosesof 5 μg or even 2.5 μg per unit administration.

A further possibility consists of keeping the same excipient andvectorizing the active principle instead of it being in its free form inthe vehicle.

The importance of such vectorization and the manner of obtaining it areexplained below.

Vectorization of 17β-estradiol

One aim of vectorization of 17β-estradiol is to eliminate systemicpassage of the active principle by more gradual release of the latterwhich "spreads" the plasmic peak by reducing its maximum amplitude,which should permanently remain below 50 pg/ml of plasmic concentration.

Vectorization advantageously also prolongs the duration of the localaction of the active principle.

These two aims can be achieved as follows.

In order to prevent any systemic passage, the vector must besufficiently large not to pass through the vaginal epithelium. A sizewhich is of the order of 200 nanometers (nm) in diameter satisfies thiscriterion. The vector must, of course, be compatible with 17β-estradiol,allowing its gradual distribution, it must be compatible with vaginalmucus and it must be perfectly tolerated.

In order to increase the period of action, an electrostatic interactionbioadhesion system can be selected. Under normal conditions, vaginalmucus is acidic in nature (pH of the order of 4) while during themenopause this pH has a tendency to increase to about 6. It is thusadvantageous to provide the periphery of the vector with positivecharges which can then interact with the negative charges on the mucus.

It should be noted that the acidic properties required for maximalinteraction between the mucus and the vector are reduced during themenopause (pH of the order of 6) but these low acidity conditions may besufficient for effective interaction with the vectors.

An example of a vector which satisfies these different conditions is oneconstituted by nanoparticles (i.e., particles with a diameter of theorder of a few tens or at most a few hundreds of nanometers) such as the"Supramolecular biovectors" (SMBV) described in International patentapplication WO-A-89/11271 (Centre national de la recherche scientifique)and products from Biovector Therapeutics S.A.

These SMBV, which are known vectors, comprise a non liquid hydrophilicnucleus, an inner lipid envelope bonded to the nucleus by covalent bondsand an outer amphiphilic envelope bonded to the inner lipid envelope byhydrophobic interactions.

These vectors can be charged with active principle, in this case17β-estradiol (which is a lipophile) encapsulated in the vector, theensemble thus constituting a biomimetic active principle transporterwhich mimics endogenous transport systems such as lipoproteins.

EXAMPLE OF A SOFT CAPSULE FORMULATION

In order to satisfy the concept of bioadhesion of the galenicalformulation of the invention and prevent flow to a maximum extent, inthis example the inner phase of this soft capsule comprisesbiocompatible hydrophilic gel-forming bioadhesive polymers which canincorporate the moisture in vaginal secretions to a maximum extent toincrease the viscosity and thus prolong in situ retention of theemulsion.

Flow of the lipophilic contents of the inner phase of the capsule isprevented by using a gelling agent for this lipophilic agent. In thisexample, at least one of the ingredients in the inner phase encouragesemulsification with vaginal secretions of the lipophilic derivativewhich is the main constituent of the fatty phase.

A typical composition of the inner phase is as follows:

    ______________________________________                                        Free or vectorized 17β-estradiol                                                                2.5 μg to 15 μg                                     (i.e., 1.5625 ppm to                                                          9.375 ppm)                                                                   Hydroxypropylcellulose (Klucel ® HXF) 120 mg                              Hydrophobic colloidal silica (Aerosil ® R972) 70 mg                       Polyoxyethylene glycol 7-glyceryl-cocoate 400 mg                              (Cetiol ® HE)                                                             Liquid triglycerides (Miglyol ® 812) q.s. 1600 mg                       ______________________________________                                    

Note the very low final concentration of active principle, 1.5625×10⁻⁶to 9.375×10⁻⁶ for the range of unit doses indicated above, in particular6.25×10⁻⁶ (0.000625%) in the clinical trials which are reported below.

Once prepared, this inner phase is introduced into an outer envelopecomprising gelatin/glycerine corresponding to the structure of a softcapsule.

A variety of doses of the different excipients can be envisaged. Thusthe dose of hydrophobic silica can be in the range 50 mg to 80 mg.

It is also possible to modify the composition of the excipients.

Thus the hydrophilic gel-forming bioadhesive polymer(hydroxypropylcellulose) can be replaced by other hydrophilicgel-forming bioadhesive components such as: carboxyvinylic acids,hydroxypropylcellulose, carboxymethylcellulose, gelatin, xanthane gum,guar gum, aluminum silicate or a mixture of two or more of the abovecomponents.

Regarding the hydrodispersible agent, the polyoxyethylene glycol7-glyceryl-cocoate can be replaced by a polyoxyethylene glycol (PEG).

Example of a Slow Release Vaginal Suppository Formulation

In this case, the medicament comprises a hard or semi-soft solidhomogeneous phase, a typical composition of which is as follows:

    ______________________________________                                        Free or vectorized 17β-estradiol                                                                  2.5 μg to 15 μg                                  Hydroxypropylcellulose (Klucel ® HXF) 80 mg                               Hydrophobic colloidal silica (Aerosil ® R972) 40 mg                       Polyoxyethylene glycol (PEG 400) 80 mg                                        Carboxyvinylic acid (Carbopol ® 974 P) 8 mg                               Solid triglycerides (Witespol ® S 551) q.s. 1600 mg                     ______________________________________                                    

A variety of doses of the different excipients can be envisaged. Thusthe dose of hydrophobic colloidal silica can be in the range 5 mg to 60mg, and that of PEG in the range 50 mg to 200 mg.

It is also possible to modify the composition of the excipients.

Thus the Witespol® S 51 can be replaced by carnauba wax, cocoa butter orother triglycerides with a melting point of about 35° C., for exampleOvucire® type.

The hydrophilic gel-forming bioadhesive polymers (Klucel® and Carbopol®)can be replaced by the same substituents as those indicated above in theexample of a soft capsule formulation.

Clinical Trials

Results obtained from six patients revealed the following elements:

Clinical and biological tolerance: Under the trial conditions, the localand general clinical tolerance of the above formulation of the inventionin the form of soft capsules in doses of 2.5 μg, 5 μg and 10 μg wasexcellent. No undesirable effect was reported. The biological tolerancewas excellent. No anomaly of clinical significance was reported.

Pharmacokinetic analysis: From a pharmacokinetic viewpoint, the plasmicestradiol concentrations remained unquantifiable in the group ofsubjects after administration of low doses (2.5 μg and 5 μg) and in halfof the subjects at a high dose (10 μg). In the three other subjects,estradiol quantities above the quantification limit were only measuredin a few samples (2 or 3) after treatment and did not exceed 30 pg/ml.

Regarding estrone, the concentrations measured after treatment were ingeneral of the same order of magnitude as those measured beforetreatment. When the quantities of estrone were higher after treatment (2or 3 subjects per group depending on the group), the highestconcentration did not exceed 22% (subject n° 02), 34% (subject n° 06)and 260 (subject n° 06) over the values measured before treatment, at2.5 μg, 5 μg and 10 μg of 17β-estradiol respectively. In all cases, theestrone concentrations never exceeded 30 pg/ml. An examination of theplasmic concentration profiles of estrone showed that there was noproportionality between the C_(max) or the SSC and the administereddose.

General conclusion: After a single vaginal administration of a softcapsule with 2.5 μg, 5 μg and 10 μg doses of 17β-estradiol, clinicaltolerance was excellent for the group of six subjects included in thetrial. Biological tolerance was also excellent. No anomaly of anyclinical significance was reported.

From a pharmacokinetic viewpoint, vaginal resorption of estradiol waszero after administration of capsules with 2.5 μg and 5 μg doses of17β-estradiol. After administration of the capsule with a 10 μg dose of17β-estradiol, the estradiol remained undetectable on a plasmic level inthree out of the six subjects. In the other subjects, some plasmicestrone concentrations showed that the amounts measured after treatmentwere comparable with the amounts measured before treatment. It can thusbe concluded from this study that vaginal absorption of estradiol fromsoft capsules in 2.5 μg to 10 μg doses of 17β-estradiol is substantiallyzero over the range of doses tested.

It should in particular be noted that a peak of more than 50 pg/ml, thelimit above which secondary effects may occur in certain subjects(supra) is absent. The micronized free form of 17β-estradiol has beenshown here to be completely satisfactory and does not require recourseto a vectorized form to avoid exceeding the 50 pg/ml threshold. Thisvectorized form could, however, be envisaged if the period of action ofthe active principle was to be prolonged.

I claim:
 1. A pharmaceutical medicament for local, essentiallynon-systemic, treatment of vaginal dryness, in particular in themenopausal woman, characterized by a unit galenical formulationcomprising a natural estrogen selected from the group consisting of17β-estradiol and its salts and its derivatives in solution or insuspension in a lipophilic agent, with an estrogen content whichcorresponds to an equivalent unit dose of at most 15 μg, preferably lessthan 10 μg, of 17β-estradiol, a hydrophilic gel-forming bioadhesiveagent, a gelling agent for the lipophilic agent, and a hydrodispersibleagent.
 2. The medicament of claim 1, in which the estrogen is present inits free form.
 3. The medicament of claim 1, in which the estrogen ispresent in its vectorized form.
 4. The medicament of claim 3, in whichthe estrogen is vectorized by encapsulation in nanoparticle typevectors.
 5. The medicament of claim 4, in which the estrogen isvectorized by encapsulation in particulate supramolecular biovector typevectors.
 6. The medicament of claim 1, in capsule form comprising a hardor soft solid outer envelope containing gelatin and a non aqueous liquidor semi-liquid inner phase containing the lipophilic agent with theestrogen in solution or in suspension, the hydrophilic gel-formingbioadhesive agent, the gelling agent for the lipophilic agent and thehydrodispersible agent.
 7. The medicament of claim 6, in the form of asoft capsule, in which the outer envelope contains glycerine.
 8. Themedicament of claim 6, in which the lipophilic agent is selected fromliquid triglycerides.
 9. The medicament of claim 6, in which thehydrophilic gel-forming bioadhesive agent is selected from the groupconsisting of carboxyvinylic acids, hydroxypropylcellulose,carboxymethylcellulose, gelatin, xanthane gum, guar gum, aluminumsilicate and mixtures thereof.
 10. The medicament of claim 6, in whichthe gelling agent for the lipophilic agent is hydrophobic colloidalsilica.
 11. The medicament of claim 6, in which the hydrodispersibleagent is selected from the group consisting of polyoxyethylene glycols,polyoxyethylene glycol 7-glyceryl-cocoate and mixtures thereof.
 12. Themedicament of claim 6, in which the composition of the inner phase is:

    ______________________________________                                        Free or vectorized 17β-estradiol                                                                2.5 μg to 15 μg                                    Hydroxypropylcellulose 120 mg                                                 Hydrophobic colloidal silica 50 mg to 80 mg                                   Polyoxyethylene glycol 7-glyceryl-cocoate 400 mg                              Liquid triglycerides q.s. 1600 mg.                                          ______________________________________                                    


13. The medicament of claim 1, in the form of a slow release vaginalsuppository comprising a non aqueous hard or semi-soft solid homogeneousphase containing the lipophilic agent with the estrogen in solution orin suspension, the hydrophilic gel-forming bioadhesive agent, thegelling agent for the lipophilic agent and the hydrodispersible agent.14. The medicament of claim 13, in which the lipophilic agent isselected from solid triglycerides with a melting point of about 35° C.,carnauba wax, cocoa butter and mixtures thereof.
 15. The medicament ofclaim 13, in which the hydrophilic gel-forming bioadhesive agent isselected from the group consisting of carboxyvinylic acids,hydroxypropylcellulose, carboxymethylcellulose, gelatin, xanthane gum,guar gum, aluminum silicate and mixtures thereof.
 16. The medicament ofclaim 3, in which the gelling agent for the lipophilic agent ishydrophobic colloidal silica.
 17. The medicament of claim 13, whereinthe gel comprises a hydrophilic emollient component selected from thegroup consisting of glycerine, propylene glycols, polyoxyethyleneglycols, and mixtures thereof.
 18. The medicament of claim 13, in whichthe composition is:

    ______________________________________                                        Free or vectorized 17β-estradiol                                                               2.5 μg to 15 μg                                     Hydroxypropylcellulose 80 mg                                                  Hydrophobic colloidal silica 5 mg to 60 mg                                    Polyoxyethylene glycol 50 mg to 200 mg                                        Carboxyvinylic acid 8 mg                                                      Solid triglycerides q.s. 1600 mg.                                           ______________________________________                                    


19. The medicament of claim 2, in which the estrogen is micronized. 20.The medicament of claim 3, in which the estrogen is micronized.